Fill your kettle and boil it. Peel and finely chop the onion. Warm ½ tbsp oil in a pan over a medium heat and add the onion. Season with salt and pepper and fry, stirring often for 8 mins till glossy but not browned. If it starts to pick up any colour, turning the heat down.
While the onion fries, peel and grate the garlic and ginger. Finely grate the zest from the lemon. Dice the tomatoes.
Stir the garlic, ginger and lemon zest into the onion. Add 1 tbsp of the brown rice miso. Cook, stirring, for 2 mins. Tip in the tomatoes, stir well and pop a lid on the pan. Simmer for 15 mins, stirring for every so often, till the tomatoes have broken down and formed a thick sauce.
While the sauce simmers, pour hot water from the kettle into a large pan. Add a pinch of salt and bring back to the boil. When the water is boiling, add the chifferini and simmer the pasta for 8 mins till tender but with some bite.
While the pasta simmers, whisk 1 tbsp balsamic vinegar with ½ tbsp olive oil and a pinch of salt and pepper to make a dressing. Toss the salad leaves with the dressing.
Drain the pasta and tip back into the pan. Taste the tomato and miso sauce. Add a squeeze of lemon juice or a pinch of salt and pepper if you think it needs it. Pour the sauce into the pan with the pasta and toss to mix, then divide between 2 warm plates. Serve with the salad on the side, garnished with Thai basil leaves.